In-situ transmission electron microscopy (TEM) can be a powerful analytical technique for enabling insight into the nature of materials under a broad range of environmental conditions. With the development of a wide range of in-situ TEM stages and dedicated environmental TEM, it is possible to image materials under high-temperature, gas, and liquid conditions, as well as in other complex electrochemical, optical, and mechanical settings. In many of these applications, it may be desirable to capture the dynamic evolution of the microstructure with a high spatial and temporal resolution. While many developments in electron optics and the design of in-situ cells have been made, leading to significant improvements in achievable resolution, there are still many challenges associated with capturing dynamic processes with high temporal resolution.
In-situ TEM video capture can be performed with charge-coupled device (CCD) cameras. High-performance commercially available CCD cameras have readout rates in the range of a few tens of MB/s, which under appropriate binning conditions can provide a video acquisition period of around 30 ms. The introduction of direct detection cameras (DDCs) based on CMOS technology can provide an order of magnitude increase in readout rate, such that these cameras can be operated in the millisecond range. DDCs permit direct sensing of electrons without the use of a scintillator to provide electron-to-light conversion and can achieve greater sensitivity than that available using CCDs. While improving temporal resolution, DDCs can also enable electron dose reduction, another challenge for in-situ TEM imaging. A potential limitation is that as frame rates increase, image read-out can become a challenge due to the increased data rates.